In terms of life outside professional tennis, they are all still relatively young men. But in this demanding arena, the field already is closing in, the monstrous gap is closing. In a matter of a few years, there will be a handful of new names to replace them.

On Monday in Melbourne, you could see the inevitable process at work in the top half of the men's draw. Although most of those aging favorites find themselves in their usual berths in the quarterfinals, it was hardly a comfortable journey. No. 1 seed Nadal survived the longest men's three-set singles match of the fortnight so far (3 hours, 17 minutes) plus a ghastly looking blister and an unprecedented snapped shoe lace. The No. 4 Murray needed four match points -- and a cracked racket -- to get past a Lucky Loser.

Oddly enough, the exception was the No. 6-seeded Federer. He's 32 years old, but maybe now we can stop feeling sorry for him. Monday night in Rod Laver Arena, he memorably channeled the champion he once was, thrashing No. 10 seed Jo-Wilfried Tsonga 6-3 7-5, 6-4.

It was the best he has looked against a formidable opponent, he admitted, in at least a year.

"Yeah, I mean, I'm very pleased," Federer told reporters after the match. "Don't think I got broken today. That against a great player. So, yeah, I'm extremely happy how things went for me tonight. I was able to play my game, offensive, mix it up, come to the net. Yeah, I was surprised that things worked out for me."

Although the women's draw is in tatters -- No. 1 Serena Williams and No. 3 Maria Sharapova departed on consecutive days and five of the top eight seeds failed to reach the quarterfinals. Seven of the top eight men's seeds, however, are through to the final eight. No. 22 seed Grigor Dimitrov, the ascendant 22-year-old Bulgarian, is the only interloper, taking the place of fallen No. 5 seed del Potro.

The sparkling quarterfinal matchups feature Nadal versus Dimitrov, whom the Spaniard called "amazing" in his on-court interview and "the next great thing" in tennis. Murray meets the resurgent Federer and in the bottom half, it's the No. 2-seeded Djokovic opposite his dogged foil, No. 8 Stanislas Wawrinka, and No. 3 David Ferrer against No. 6 Tomas Berdych.

"It's been a good ride," Federer said. "I thought I played really well tonight. Clearly, against Jo-Willie you have to bring your best game. You have to dictate the pace."

Later, he told ESPN's Pam Shriver his mindset was, "Let me start aggressive here and see what happens. It's been a tough six months. You never know what to expect."

Tsonga forgot his Australian Open credential when he came out to the park earlier in the afternoon. Maybe he should have done without the day pass and gone back to the hotel.

Wielding a new, slightly larger racket, serve-and-volleying with abandon, on Monday night Federer aggressively attacked the net more than we are accustomed to seeing. Federer won 34 of his 41 net points, a tidy 83 percent. Maybe it's because he's healthier than he has been in recent years -- and confident, too.

"I used to serve and volley against Sampras in 2001 at Wimbledon," Federer said. "That was like 13 years ago, man. It's not like I've been standing way back in the court like some clay-courter. I've always tried to come in. I was actually coming in a lot at the beginning of my career because I didn't feel I was good enough off the baseline against the great baseliners that were still in the game in my time: Hewitt, Ferrero, Safin, Nalbandian, Agassi.

"I always felt like, 'God, these guys have such great backhands. They have such an easy time finding my backhand.' I'm coming in because I don't want to rally back there.

"Eventually in 2003 I probably realized I can actually also hang with them from the baseline and beat them. That's when everything changed. Conditions got slower. I improved from the baseline. My movement got solid. I was fit. That's then when I went on a run."

Federer broke Tsonga's very first service game and never really got off the gas.

He lost only six points on his first serve.

"I was hoping I could play a little bit aggressive," Federer said. "So I think it worked out better than I thought it would. You know, I was good at net. I was consistent. I was solid. I was quick. I had the right mindset. I think the plan definitely worked out well for me tonight."

Murray actually dropped a set to Stephane Robert, a journeyman from France who lost in qualifying before Philipp Kohlschreiber pulled out of the tournament. Robert -- who is 33 and ranked No. 119 among ATP World Tour players -- was the first Lucky Loser to reach the fourth round of the Australian Open and, for a tantalizing few minutes, it looked like he might be a threat to reach the quarters.

Murray, however, gathered himself and won 6-1, 6-2, 6-7 (6), 6-2.

When Robert's forehand finally found the net, Murray issued an emphatic "Yes!" and pumped his fist in the direction of his box, which contained a relieved coach, Ivan Lendl. The Scotsman, who missed the last three months of the 2013 season following back surgery, has won 12 of his 13 sets and perhaps his outburst at the end of the third set will help shake off the rust.

"I dominated 95 percent of the match," Murray told reporters afterward, "and for 15 minutes didn't close the match out. I was one point away from being in here and that being in here after a great performance to playing 15 minutes not perfect.

"A lot of guys sort of hold it by the throat and kind of throw it face down. That's how you would throw it if you didn't want to break the racket. Whereas if you just kind of go flat with the frame, or if you just hit the frame like that, the racket's gone straightaway."

"I think I played a little bit too short," Rafa said. "He was able to play more inside. I think he was in a better position on the points than me more times. So that's something that cannot happen. But is true that is tough to change that when the opponent is decided to hit winners from everywhere.

"Kei is a potential top-10 player. So that's the real thing."

He described the raw blister in the middle of his left hand that required attention "so-so."

Said Nadal, "The problem is not the blister. The problem is the place. Is very difficult to cover that blister here. Is not painful, but I cannot play without that cover today."